This invention relates generally to systems which generate mail pieces and is more particularly concerned with managing differences in operating rates among components of such systems.
In a typical mail-creation system, a personal computer or the like generates data that represents text and/or images to be printed on sheets of paper. A printer is in data communication with the personal computer and receives downloads of print data. The printer prints the downloaded data on sheets of paper. An inserter or other mail-assembling machinery receives, directly or indirectly, printed sheets that are outfed from the printer. The inserter folds and/or otherwise manipulates the printed sheets and inserts them in envelopes to generate mail pieces.
One issue that must usually be faced in designing a mail-creation system is that the constituent components of such a system may tend to operate at different rates. For example, the personal computer may be capable of generating pages of print data at an extremely rapid rate, reflecting the high speed of operation of modern microprocessors and other PC components. Usually the printer component of the mail-creation system is not able to operate nearly as fast as the PC. For that reason, a conventional software component known as a “spooler” is customarily included in PCs so that the PC downloads pages of print data to the printer only at a rate that matches the printer's ability to print pages.
On the other hand, it is frequently the case that inserters are capable of operating at a much faster speed than the printer component of the system. However, inserters do not always operate at their highest possible rates, but rather may be subject to hesitations or jam events which may greatly slow or even halt the inserter's operation on certain occasions. During such occasions, the printer operating rate may outstrip that of the inserter. Also, there are situations in which the inserter runs more slowly than the printer, even without hesitations or jams. For example, in a job where the inserter receives one sheet from the printer and adds more sheets from the inserter's feeder(s), the inserter may require sheets from the printer at a lower rate than the printer is capable of providing them.
There are several conventional techniques for dealing with a possible and/or temporary mismatch between the operating rates of the inserter and the printer.
According to one technique, a large mechanical sheet buffer may be installed in the paper flow path between the printer and the inserter. In this context, the term “large” indicates that the sheet buffer is able to buffer numerous printed sheets of paper after the same are outfed from the printer and before the sheets are infed to the inserter. This technique may be disadvantageous in that the sheet buffer may be quite expensive and may occupy a great deal of space. Moreover, this technique cannot cope with a situation where the steady-state operating rate of the inserter is less than that of the printer, since the buffer is virtually certain to overflow in such a case.
According to a second technique, a sheet-diversion mechanism may be coupled to the paper feed path between the printer and the inserter. The sheet-diversion mechanism may operate to divert the flow of sheets away from the inserter on occasions when the inserter operating rate effectively falls behind that of the printer. Data to generate duplicates of the diverted sheets may be downloaded to the printer from the PC once the inserter recovers its normal operating speed. The diverted sheets may be discarded.
One disadvantage of the latter technique is possible wastage of the diverted sheets. Further, it may not be practical to employ this technique when it is intended that the mail pieces be produced in a fixed order. In the situation where the steady-state operating rate of the inserter is less than that of the printer, this technique would require diverting sheets on a regular basis.
A third technique calls for a control signal connection from the inserter control device back to the printer. For this technique a customized firmware program is incorporated in the printer to allow the operation of the printer to be halted or slowed down in response to a control signal from the inserter control device when the inserter control device detects a need to do so on account of an event in the inserter. A disadvantage with respect to this technique may be encountered if it is desired to replace the printer in the mail-creation system with a different model of printer. The expense and time required to write the necessary custom firmware for the desired replacement printer may increase the cost and lead time entailed by introducing the new printer into the mail-creation system.